(1) Field of the Invention:
This invention relates to a can interior coating composition suitably applicable to a very short time curing process, and more particularly to the can interior coating composition which exhibits such properties as excellent at hygienic properties, retorting resistant properties, adhesion properties, process ability, flavor properties, corrosion resistance, water resistance and the like when applied to the very short time curing process.
(2) Description of the Prior Art:
The widely known can interior coating compositions for coating an interior surface of a can for use in canning etc. include mixtures of a high molecular weight epoxy resin having an epoxy equivalent of 1,650 to 3,500 with at least one resin component selected from a group consisting of a resol phenol resin and an amino resin, or precondensates thereof.
Japanese Patent Application Laid-Open No. 142068/88 discloses for the purpose of providing improved retorting resistant properties a method of utilizing mixtures of a reaction product which is obtained by a reaction between epichlorohydrin and bisphenol compounds and terminal groups of which are mostly phenolic hydroxyl group, with at least one resin component selected from a group consisting of a resol phenol resin and an amino resin, or precondensates thereof.
Recently, however, many processes, in which curing is carried out during a very short period of time after coating the can interior coating composition, have been employed to meet needs of improvement in productivity and of cost down from can makers.
Specifically, the curing has recently been carried out for such a short period of time as 20 to 30 seconds compared with 90 to 120 seconds in the previous processes.
It has been pointed out that the can interior coating composition in the prior art raises problems caused by the use of the conventional resol resin, i.e. problems that such performances as at potassium permanganate consumed, flavor properties and the like are unsatisfactory to meet the above needs.
Moreover, problems of process ability, adhesion properties, retorting resistant properties, corrosion resistance and the like remain unsolved because of lack of sufficient time period to cure after coating the can interior coating composition.